This tutorial review discusses recent advances in the chemical synthesis and potential applications of monodisperse magnetic nanoparticles. It begins with an introduction to nanomagnetism, highlighting the unique magnetic properties of nanoparticles due to their size being comparable to the magnetic domain size. The review then focuses on recent developments in solution-phase syntheses of monodisperse MFe2O4, Co, Fe, CoFe, FePt, and SmCo5 nanoparticles, detailing their surface, structural, and magnetic properties for biomedicine and magnetic energy storage applications. The chemical synthesis methods for magnetic nanoparticles are reviewed, including thermal decomposition of organometallic precursors and metal salt reduction. The importance of surfactants in preventing agglomeration and stabilizing nanoparticles is emphasized. Recent advances in monodisperse Fe, Co, and FePt nanoparticles are discussed, along with the challenges and solutions for stabilizing these nanoparticles. The review also covers the biomedical applications of superparamagnetic nanoparticles, particularly in MRI contrast enhancement and magnetic fluid hyperthermia. Surface functionalization techniques, such as surfactant addition and surfactant exchange, are described to make these nanoparticles hydrophilic for biological applications. The magnetic properties of these nanoparticles, including their relaxation times and contrast effects in MRI, are discussed. Finally, the review explores the use of magnetic nanoparticles in exchange-spring composite magnets for energy storage applications. The binary assembly of magnetic nanoparticles and the formation of exchange-coupled nanocomposites are discussed, highlighting the enhanced magnetic properties achieved through this approach. The review concludes by emphasizing the potential of magnetic nanoparticles for ultra-high density information storage, highly sensitive medical diagnostics, and efficient therapeutic applications.This tutorial review discusses recent advances in the chemical synthesis and potential applications of monodisperse magnetic nanoparticles. It begins with an introduction to nanomagnetism, highlighting the unique magnetic properties of nanoparticles due to their size being comparable to the magnetic domain size. The review then focuses on recent developments in solution-phase syntheses of monodisperse MFe2O4, Co, Fe, CoFe, FePt, and SmCo5 nanoparticles, detailing their surface, structural, and magnetic properties for biomedicine and magnetic energy storage applications. The chemical synthesis methods for magnetic nanoparticles are reviewed, including thermal decomposition of organometallic precursors and metal salt reduction. The importance of surfactants in preventing agglomeration and stabilizing nanoparticles is emphasized. Recent advances in monodisperse Fe, Co, and FePt nanoparticles are discussed, along with the challenges and solutions for stabilizing these nanoparticles. The review also covers the biomedical applications of superparamagnetic nanoparticles, particularly in MRI contrast enhancement and magnetic fluid hyperthermia. Surface functionalization techniques, such as surfactant addition and surfactant exchange, are described to make these nanoparticles hydrophilic for biological applications. The magnetic properties of these nanoparticles, including their relaxation times and contrast effects in MRI, are discussed. Finally, the review explores the use of magnetic nanoparticles in exchange-spring composite magnets for energy storage applications. The binary assembly of magnetic nanoparticles and the formation of exchange-coupled nanocomposites are discussed, highlighting the enhanced magnetic properties achieved through this approach. The review concludes by emphasizing the potential of magnetic nanoparticles for ultra-high density information storage, highly sensitive medical diagnostics, and efficient therapeutic applications.